Assembly of Rolled-Up Collagen Constructs on Porous Alumina Textiles

Developing new techniques to prepare free-standing tubular scaffolds has always been a challenge in the field of regenerative medicine. Here, we report a new and simple way to prepare free-standing collagen constructs with rolled-up architecture by self-assembling nanofibers on porous alumina (Al₂O₃) textiles modified with different silanes, carbon or gold. Following self-assembly and cross-linking with glutaraldehyde, collagen nanofibers spontaneously rolled up on the modified Al₂O₃ textiles and detached. The resulting collagen constructs had an inner diameter of approximately 2 to 4 mm in a rolled-up state and could be easily detached from the underlying textiles. Mechanical testing of wet collagen scaffolds following detachment yielded mean values of 3.5 ± 1.9 MPa for the tensile strength, 41.0 ± 20.8 MPa for the Young's modulus and 8.1 ± 3.7% for the elongation at break. No roll-up was observed on Al₂O₃ textiles without any modification, where collagen did not assemble into fibers, either. Blends of collagen and chitosan were also found to roll into fibrous constructs on silanized Al₂O₃ textiles, while fibrinogen nanofibers or blends of collagen and elastin did not yield such structures. Based on these differences, we hypothesize that textile surface charge and protein charge, in combination with the porous architecture of protein nanofibers and differences in mechanical strain, are key factors in inducing a scaffold roll-up. Further studies are required to develop the observed roll-up effect into a reproducible biofabrication process that can enable the controlled production of free-standing collagen-based tubes for soft tissue engineering.